This practical guideline establishes definitions for “contact”, “contact person”, “contact tracing” and other associated concepts. It allows for improvement of contact tracing strategies and provides recommendations attempting to answer some, though not all, questions that arose during the 2019 coronavirus pandemic and other outbreaks. The use of this guideline begins once people have been diagnosed and the potential for transmission exists. It is not, however, intended to assist with case investigation. The guideline empowers health workers, governments, and public health officials with the tools to implement effective contact tracing strategies.